Chocolate Mousse

Many of the fine-quality bittersweet chocolates sold at supermarkets typically contain 50 to 60 percent cocoa solids. If you choose chocolate with a higher percentage, your mousse may be slightly denser.

Preparation

Heat 3/4 cup cream in a 1-quart heavy saucepan until hot. Whisk together yolks, sugar, and a pinch of salt in a metal bowl until combined well, then add hot cream in a slow stream, whisking until combined. Transfer mixture to saucepan and cook over moderately low heat, stirring constantly, until it registers 160°F on thermometer. Pour custard through a fine-mesh sieve into a bowl and stir in vanilla.

Melt chocolate in a double boiler or a metal bowl set over a pan of simmering water (or in a glass bowl in a microwave at 50 percent power 3 to 5 minutes), stirring frequently. Whisk custard into chocolate until smooth, then cool.

Beat remaining 1 1/4 cups cream in a bowl with an electric mixer until it just holds stiff peaks. Whisk one fourth of cream into chocolate custard to lighten, then fold in remaining cream gently but thoroughly.

 To vary the flavor, you can replace the 1 teaspoon vanilla with 2 teaspoons instant-espresso powder (dissolve it in the hot cream) or 3 tablespoons Grand Marnier or 2 tablespoons Cognac (either one whisked into strained custard).